土壤水实验设备负压边界调控方法  

Method of controlling negative pressures at the boundary of soil water experiment equipments

作　　者：黄汉生[1] 杨何畏 王康[1] HUANG Hansheng;YANG Hewei;WANG Kang(School of Water Resources and Hydropower Engineering,Wuhan University,Wuhan 430072,China;Hubei Water Conservancy and Hydropower Research Institute,Wuhan 430070,China)

机构地区：[1]武汉大学水利水电学院,湖北武汉430072 [2]湖北省水利水电科学研究院,湖北武汉430070

出　　处：《实验技术与管理》2023年第3期32-36,共5页Experimental Technology and Management

基　　金：国家自然科学基金项目(51879195)。

摘　　要：对于大型蒸渗仪等土壤水分和溶质迁移模拟实验设备,实现其负压边界条件控制,将显著地提升实验的仿真性。该文根据真空气室-陶瓷膜-土壤多相介质条件下负压传递原理,研发了一种负压边界调控装置。在真空气室控制负压分别为–15、–30和–50kPa条件下,对土壤边界层的负压调控效果如土壤负压控制的均匀性和稳定性进行了测试。结果表明:实验土壤条件下,采用真空气室-陶瓷膜-土壤的负压传递形式,能够形成稳定的土壤负压一类边界条件;负压控制效果主要受土壤质地和陶瓷膜传输性质的影响,土壤与真空气室负压差随真空气室内负压增加而表现出先减小,后增加的趋势,土壤边界负压相比真空气室内的控制负压平均降低了20%;土壤边界均匀性主要受到不同位置控制面形成的负压叠加,以及土壤中负压的传输与土壤基质势均衡速率两个因素的影响,负压控制稳定性主要受土壤介质性质的影响;均匀度的控制水平达到0.7,稳定性系统偏差小于6.8%。该文所提出的方法能够有效地实现土壤边界的负压控制。The realization of controlling the negative pressure at the boundaries will significantly improve the simulation functions of the large-scale lysimeters and other soil moisture and solute migration simulation equipments.In this paper,a negative pressure boundary controlling device is developed based on the principle of negative pressure transfer under the condition of vacuum chamber,ceramic membrane and soil multiphase medium.The performances of the device(i.e.,the uniformity and stability of soil negative pressure)are evaluated under the conditions that the negative pressures in the vacuum chamber are–15,–30 and–50 kPa,respectively.The results show that under the experimental soil conditions,the negative pressure transfer in the vacuum chamber-ceramic membrane-soil can maintain soil pressure in the sit value.The negative pressure at the boundary is mainly affected by the soil texture and the transmission property of the ceramic membrane.The difference in negative pressure between the soil and the vacuum chamber decreases firstly and then increases with the increase of the negative pressure in the vacuum chamber.Compared with the negative pressure in the vacuum chamber,the negative pressure at the boundary reduced 20%on average.The uniformity of the soil potential at the boundary is mainly influced by the transmission of negative pressure in the soil,the equilibrium rate of soil matrix potential and the hydraulic properties of the ceramic membrane.The stability of the soil potential is primarily affected by the properties of soil medium.The uniformity of the device reaches 0.7 and the systematic deviation is less than 6.8%,indicating that the device can be used to regulate and control the negative pressure in soil at the boundary layers.

关 键 词：负压边界控制 土壤水势 稳定性与均匀性 大型蒸渗仪 

分 类 号：S152.7[农业科学—土壤学]